Fuel pump problems?

[billp]

Thanks everyone. Some good suggestions and maybe an electric pump would be good. I certainly don't wish to go down the 'Easystart' route as that would mean removing the bonnet and then the air cleaner each time. A solution to not removing the bonnet is what I'm looking for. Like Vyv, I can't see how the fuel in the carb evaporates - there must be a tiny vent so that an empty carb can fill. I must say that I do not have the problem during the summer when using the car, only when it hasn't been used for a number of weeks. Logic dictates that even if the pump allowed leak back to the tank then I can appreciate that the pump will be trying to pump air and that is why it takes so long to fill the carb float chamber - but why is the float chamber empty. Even with leak back from the pump, the fuel in the carb should remain and I just cannot see where it can go. However, I have several SU pumps and have rebuilt them in the past, so will investigate that solution first.

[howardjs]

After 1 day between engine runs my SU will pump for 3 to 4 clicks before stopping. After 1 week (approx) the pump will click rapidly maybe 10 or 15 times before stopping. So, the fuel in the float chamber is definitely going somewhere. There is a vent in the float chamber top to allow the fuel to enter until the float valve closes, (in the case of a SU HS it's behind the small cover plate where the filler tube enters the chamber top) therefore the fuel is probably evaporating from chamber over time. Even so, with the SU pump it is not necessary to wait until the chamber is full to start the engine, as soon as the SU starts so will the engine.
I have had many cars over the years with mechanical pumps and all gave winter starting headaches, cranking leading to flat batteries... and if you are unfortunate enough to run out..!
So electric V mechanical... it is Electric 1 Mechanical 0 in my view.
Howard

[llanigraham]

I'm sorry but 40 years experience shows me that petrol in a carb DOES evaporate.
No carb is totally air tight since there is a tiny hole in the jet otherwise it wouldn't be able to inject fuel into the airstream, plus there is a pipe running from the carb back to the petrol tank, so even that pipe will be subject to some evaporation.
I can also tell you that some carbs are worse than others for evaporation. From my experience SU's and Solex are far worse than Webers. And don't ever think about Jikov ones!

[motomallett]

Hi Guys there seems to be a lot of talk about evaporation. Surely it is a problem for those that keep their car in the garage all year instead of being out on the open road. As i know for a fact that this does not apply to Bill, he uses his car at every opportunity. Might i suggest an electronic pump that has been fitted on my PAC for many years and has always been an instant starter. regards Roger

[Jack602]

Having heard about this issue, on my Pembleton I used a replacement 2cv mechanical fuel pump with a hand primer lever, supplied by Der Franzose in Germany.
A couple of pumps on the priming lever & car starts straight away after being left standing.

Jack
Pembleton Super Sport "Mon Petite"

[notsmartcar]

What a great piece of advice jack

[billp]

thanks for that Jack, in the end I've fitted a hand primer bulb below to pump, as they have a non-return valve in them so that should stop any fuel bleed back to the tank from the pump. A couple of pumps and the fuel pump is primed as is the carb - works great

[tony-morony]

I've been watching this thread with interest as I too have been having starting problems after a few weeks lay off. Last summer I fitted one of the non return bulb pumps which seemed to have very little effect. I would squeeze the bulb several times until I felt resistance but I still ended up turning the engine over for thirty seconds plus before it would fire up, (and yes, it was fitted the right way round). I have now just received, (today), a new pump with hand lever from Der Franzose. The plan is to fit the pump with a choke cable like setup so I can operate it from the cockpit while turning the engine over. I'll keep you posted.
Tony

[tony-morony]

Update on the fuel pump. Fitted the new Der Franzose pump to the Lomax this morning. I made a point of not trying to start the car before fitting so it has not been struck up since the New Year, (yes I know, wussy fair weather driver). Anyway, bolted straight on, no problem. Half a dozen pumps of the lever, twisted the key and, .......nothing! Battery flat as a pancake. Connected the jump leads up to my van and the car burst into life at, quite literally, the fist revolution of the engine. Well chuffed. All l have to do now is find a way to rig a remote cable onto the dashboard............
Tony

[Lomax76]

Good move for sure, I,ll have to do the same. But building a remote from the dashboard might not be an issue as of using it once on the blue moon thus it is a good idea to have a butcher's under the bonnet see if everything is in order, is it not? An oil check wont give any harm.